Circuit breaker



Sept. 14, 1954 T. M. COLE 2,689,286

CIRCUIT BREAKER Filed March 8, 1952 H2 54 ,ff/5.1. 34

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INVENTOR. 714/0414.;- ,m cams BYglMn.. M f- Patented Sept. 14, 1954CIRCUIT BREAKER Thomas M. Cole, New York,-N. Y., assignor to FederalElectric Products Company, Newark, N. J., a corporation of DelawareApplication March 8, 1952, Serial No. 275,580

(Cl. 20G-116) 17 Claims.

This invention relates to automatic circuit breakers and moreparticularly, but without restriction,v to circuit breakers of thegeneral type disclosed in United States Patent Re. No. 23,188.

The present invention is a continuation-im part of my co-pendingapplications Serial No. 127,433, led- November 15, 1949, now Patent No.27,647,186, dated July 28, 1953, and Serial No. 184,749-, filedSeptember 14, 1950, both assigned to the assignee hereof.

One object of the present invention is to provide circuit breakers whichare automatically tripped by the-operation of a thermostatic controldevice and which areof such character that breakers of different ratingsmay be produced without requiring variations in the control device'.

Another object is to enable circuit breakers of different ratings to beproduced from. component parts of the same size and shape. Therefore,Ythe primary obj ect of the present invention istheprovision of means,other than thermal-current responsive members for setting the currentratings of circuit. breakers.

Another object` sthe provision of means for calibratingY acircuitbreaker without the necessity of effecting any changes orvariations in the movable switch arm or in the control device thereof.

A` further Object is the provision of an. improved movable switch memberfor a circuit breaker, which obviates the need forl insulating from'said switch member, the actuator which is pivotally mounted thereon.

rEhe above and other obects, features and advantages of' the presentinvention will bev more fully understood from the following descriptionconsidered` in connection with the accompanying illustrative drawings;

In the drawings: f

Fig. 1 is a side view oi a circuit breaker, pursuant to an embodiment ofthe present invention, one part of the casing being removed, the circuitbreaker being in the closedv or circuit making. conditionY thereof.;

2 is an end view of the circuit breaker taken in the direction ofA thearrows 2 2l in Fig. 1;

Fis". Bis. a sectionall view taken on the line .ii- 3 of Fig. 1;

Fig. 4 is a view similar to Fig. 1 Aillustrating another embodiment ofthe invention; and

Fig. 5 is av sectional view taken on the line 5--5 of` Fig. 4.

Referring now to Figs. l through 3 of the drawings in detail, the,`circuit breakermechanism of the present invention is disposedwithin achamber l0 defined in a two-.part insulation housing or casing l2comprising a body part lli and a cover or closure part i6. As hereinillustrated, the circuit breaker is of the plug-in type, being providedwith a plug-in terminal prong or stab contact I8 extending from thecasing i2 for making contact with a terminal plate assembly, such asthat described in the United States application Serial No. 127,432, ledNovember 15, 1949, by Paul M. Christensen and myself, as jointinventors, now Patent No. 2,647,225, dated July 28, 1953, and assignedto the assignee of the present application. However, it will beunderstood that the present invention is not limited to circuit breakersof the plug-in type but is applicable, as will be shown, to circuitbreakers which are not provided with plug-in terminals, the stabcontact, per se, not forming a part of the invention to which thisapplication is directed.

The casing is provided with an arcing chamber 20 in which the stationarycontact 22 and the companion movable contact 2li of the circuit breakermechanism are disposed for relative movement. A terminal member 26,provided with a terminal screw 28, is mounted in a recess 30 formed inthe casing, above the arcing chamber 2U. Said terminal member mounts thestationary contact 22. The casing is also provided with' an opening 32through which an insulated pivoted handle 34 projects for manualoperation of the circuit breaker mechanism, said handle being mountedillustrated and described in my copending Patent No. 2,647,186.

Referring now to the circuit breaker mechanism disposed in chamber l,said mechanism includes a manually operable member, here shown as thepreviously mentioned pivoted handle Se. A movable switch member or arm36 is mounted in chamber lll for pivotal movement on pivot pin 35, theopposite ends of which are received in the casing parts,Y as illustratedand described in my Patent No. 2,647,186. At one end thereof, switchmember 36 carries the contact 241 which is engageable with anddisengageable from the companion stationary contact 22. Athermal-current responsive control member ri, here shown as athermostatic, bimetallic, flexible strip, is secured in a suitablemanner to a side edge of the switch member The free end of lai-metallicstrip lil! is arranged to releasably engage the latch element 42 at oneend of an actuating member or lever 44, pivotally mounted on the end ofthe movable switch member 36, opposite the end which carries the contact2t.

As here shown, and as illustrated and described in detail in myco-pending Patent No. 2,647,186,

the actuator 44 is preferably formed in one piece of sheet metal andcomprises the laterally spaced opposing walls 46 and 48 open between themarginal edges 50 and 52 thereof, and partially closed between theopposed marginal edges thereof by the integral wall 54 which is providedwith the aforementioned latch element 42, depending below said opposingwalls, and with the longitudinal reinforcing bead 56 offset laterallyoutwardly thereof. The walls 50 and 52 are provided with the confrontingpunched-in projections 58-58 which are mounted for pivotal movement in abearing aperture 60 provided in the movable switch member 3B.

When lever 44 is mounted on the switch member 36, the walls 50 and 52thereof straddle said movable switch member. At their free ends, each ofsaid walls is provided with an aperture 62. One end 64 (Fig. 5) of aresilient link 66 extends with a slight clearance through the alignedapertures 62 and the other end of said link is pivotally engaged withthe handle 34. A coil compression spring 68 is operatively interposedbetween the movable switch member 36 and the handle 34 for biasing themovable switch member to its open position. One end of said springengages a lug carried by handle 34 and the other end of said springengages a lug 12 integral with the movable switch member 36. Themechanism constituted by handle 34, movable with switch member 36,thermal strip 40, lever 44, and link 66 is similar to and operates insubstantially the same way as corresponding mechanism in the aboveidentified United States Patent Re. No. 23,188.

It will be understood that member 40 operates to latch the manuallyoperable actuating mechanism 44 to the movable switch member 36 and tounlatch the actuating mechanism from the movable switch member, theunlatching taking place upon the deflection of member 40 causing thedisengagement of the free end thereof from the edge of latch element 42of lever 44 upon the occurrence of an overload, or under other Vabnormalpredetermined conditions of the circuit controlled by the circuitbreaker. When the member 40 is deilected from engagement with lever 44,spring 68 is effective to move contact member 36 to its open circuitposition from the closed circuit position thereof illustrated in Figs. 1and 4. Calibration means, such as the peripherally interrupted aperture14 and a tapered pin 16, illustrated and described in detail in myco-pending Patent No. 2,647,186, may be provided in the movable contactmember 36 for Calibrating the circuit breaker.

The control element 40 is connected in series with movable contactmember 36 and the circuit which is to be controlled by the circuitbreaker. For this purpose a flexible metallic conductor or connector 18is connected to said control element, preferably adjacent the free endthereof. The other end of the connector is connected to the previouslymentioned stab contact I8 to complete a circuit between the terminals 26and I8 when the breaker is closed.

Pursuant to the embodiment illustrated in Fig. l, the movable switchmember 36, formed in one piece, is provided with a portion 80 having ahigh resistance to the flow of current therethrough and a portion 82 inseries therewith and having a low resistance to current flowtherethrough. Specically, the resistance of portion 80 is preferably ofsuch a value as to substantially prevent the passage of current throughtion, bronze or other similar metal.

the movable switch member 36. Said portion may be formed of any suitablehigh resistance metal, such as, for example and without limitation,Nichrome or other similar metal, and the portion 82 is formed of asuitable low resistance metal, such as, for example and without limita-Said two portions are secured to each other in edge to edge relation, asat 83, in any suitable way, for example, by welding or brazing. It willalso be understood that the switch member 36 may be formed of powderedmetal by a molding operation, with parts 8|! and 82 formed of metalpowder having high and low resistances, respectively. It will be notedthat the low resistance portion 82 is provided with the movable contact24 and with the thermal strip 40, whereby substantially all of thecurrent which is flowing through the circuit which is controlled by thecircuit breaker will flow through the thermal strip 40. though the strip40 is in electrical contact with the movable switch member 36 throughthe lever 44, in the closed condition of the circuit breaker, it will beunderstood that due to the high resistance characteristics of thematerial which forms the portion 80 of said switch member, the currentwill not bypass the strip 40 by flowing through the lever 44, butsubstantially all of the current will flow through the engaged contacts22 and 24, the portion 82 and the strip 40. In this connection, it willbe noted that since substantially no current flows through the lever 44,because of the high resistance characteristics of the portion 80, theusual insulating bushing which has heretofore been provided between thelever 44 and the movable switch member 36 may be omitted so that saidlever is in direct contact with the movable switch member, asillustrated in Fig. 3.

The embodiment illustrated in Fig. 1 is preferably calibrated throughthe use of the tapering pin 16 in the peripherally interrupted aperture14 whereby to vary the extent of overlap of the latch 42 and the freeend of the strip 40, as described in detail in my Patent No. 2,647,188.

Referring now to the embodiment illustrated in Figs. 4 and 5, thecircuit breaker thereof is substantially similar in construction to thatillustrated in Fig. 1. However, pursuant to the present embodiment, aninsulated bushing 84 (Fig. 5) is interposed between the actuator 44 andthe movable switch member 36A so as to prevent the flow of currentbetween the actuator and the terminal strip 40. Also in the presentembodiment, although the movable switch member 36A is formed of theseparate portions 80A and 82A, it will be understood that the portion80A is not of such high resistance as to prevent the passage of currenttherethrough. More specifically, the portion 82A which carries themovable contact 24 and the terminal strip 40, may be formed fromv ametal of one resistance and the portion v80A may be formed of a metal ofhigher or lower resistance to provide a predetermined overall resistancefor the switch member 36A. By varying the resistance of either of theseportions, for example, but not by way of limitation, by changing therelative dimensions thereof or by changing the respective metals ofeither or both portions, the current flow through the switch member 36Amay be varied in order to vary the amount of current flow .through thebi-metallic strip 40 whereby to vary the response of the circuitbreaker. In this connection, it

masones twill ibe noted that since the :insulation bushing 284iis'interposed 'between the .actuator M .andthe -movable switch member336A, la lrlexib'le Sconnector 'or .'coup'ling 186 interconnects the'portion EUA-of the .switchmemb'er 36A, as -at 81,1and :the f fstabcontact 18, las at 189, lto :complete .a path yfor current flow throughthe :engaged contacts, Vthe :portions 182A .and 1180A and the .flexibleconnector 58B, *which path is 1in parallel with a second currentow'circuit vvhich vextends through :the-engaged fcontacts, the portionf82A, the strip 4U Aandfthei'i'lexible connector :18. Therefore, it will*be apparent that "by varying the overall current Ic'onductivecharacteristic of the switch member I3'6A, by'varying the resistance ofeither :or both -o'f the Iportions :80A and. f8'2A thereof, the -overallresponse of the Ycircuit br'eaker may be varied, asidesired, in order'to provide a desired calibration :or -fcurrent .rating vfor the circuitbreaker.

In `addition 'to fcalibrating the circuit breaker `:illustrated lin Fig.4 by varying the resistance of .either or fbo'th Jpor'tions `o'i theVmovable fswitch member i3 EA, whereby Sto vary the overall currentIconductive characteristics thereof, thefcalibration i may -alsoLbe'changed by .changing the resistance yunderlying .idea vor:principles of the invention Fwithin thescope of :the appended claims.

Having thus described my invention, what I Aclaim'and desire `to secureby .Letters Patent, :is: 1. A movable vswitch ymember Afor a ncircuitbreaker, said lmember being iunita'ry and having yintegral serially'related portions lwhich diner,

"respectively, in `current-concluetive :characteristics.

,-2. ,A movable :switch member -ior a circuit breaker', vsaid memberbeing unitary and `han/ing .portions which ldifer, respectively, :incurrent "conductive characteristics, .said portions :being .joined toeachother infielge to edgelrelation.

3. A 'movable `svsritch 'member for a circuit breaker, said member beinga planar part and having portions disposed .in 'serie-s therein .and

which fdiifer, :respectively, :in current-conductive 'characteristicsgatfleastfone .of said portions `being of 'such resistance value =as tosubstantially prevent 'the `'flowof current through saidmember.

4. A (movable `switch. lmember :for a Icircuit breaker, :said 'memberbeing `unitary fand having integral serially related portions whichAdiffer, iespectively, .in current-conductive characteristics, theconductivity .of rsaidportions being related .to provide ia:predetermined overall current-conduc- `tive :characteristic for saidswitch member.

l5. `A movable switch member .for .a 'circuit breaker, said member`being unitary 'and :having integral serially `related portions 'whichdiffer, respectively, in current conductive fcharacteristics, tone ofsaid portions being of :substantially low `current'conductivity andanother :of :said portions 'being'oi ysubstantially highcurrent-'conductivity.

-6. :In a circuit :breaker vhaving 4relatively :mov-

4able .companionfcontactsengageable-withandldisengageabl'e from 'e'achother, Aactuating :means Afor operatively effecting `:said engagement:and disentga'gem'ent thereof, Sand control means Iof :predeterminedicurrent-xconductive characteristic for eiiecting `the disengagement ofsaid contacts in response rt'o lpredetermined current in -the fcircuit;a movable switch member yof ypredetermined current-conductivecharacteristic, said switch `mem- 'ber'being .provided with oneof Asaidcontactsfsaid switch `member mounting said control .mea-ns .and Isaid:actuating :means or normal lengagementof lsaid `control 'means withsaid actuating rmeans 'to `releasably latch said `switch member to saidactuating "means for operation )by the latter, a terminal elementelectrically 'connected to said v'con- 'trolirnea'ns to `form airstcircuit in said breaker in .the closed :condition thereof, said circuit-extending from the engaged contacts to vsaid :'element and includingsaid control means, andfconnector means having a vpredeterminedresistance and electricallyconnecting said element andsaid switch memberto -form a second circuit between said element and said engaged contactswhich Iby-passes said control means vwhereby the current .rating of thebreaker is a function of the current-'conductive .characteristic ofrsaidconnec- `torfmeans.

'7. In a circuit breaker having relatively movable companion contactsengageable with and disengageable `from eachother, actuating 4means lforoperatively eiecting said engagement and disengagement thereof,andcontrol means of -pre- 'determined vcurrent*conductive characteristicfor `effecting the disengagement', Vof said contacts in response topredetermined current in the circuit; a movable switch member of-predeterminedcurrent-conductive characteristic, said switch .mem- `berbeing :provided with one of vsaid contacts, said switch member`mounting:saidfcontrol means and said actuating means for normalengagementof said :control .means with said actuating vmeans Atoreleasably latch said :switch member to said ractuating means 'for`operation fby the latter, a ter'l minal element electricallyv'connected to said Vcontrol means Yto form ya first circuit in saidbreaker :in `the closed Vcondition thereof, said ycircuit 'eX-`tending.from theiengagedcontacts-to said element 4and inoludingsaidcontrol means, randconnector `means hav-ing .a predetermined .resistance:and electrically connecting lsaid :element and .said switch .member -toterm a second -circuit between said elementand said yengagedfcontactswhich byfpasses v.said control means whereby the vcurrent rating of thebreaker is a -function ofthe currentyconcuictive characteristic-ofsaidconnectoraneans,

,member sand xoper-able 'upon overload -to release said actuating meansfor opening the circuit,rand a terminal element in circuit with saidcontrol device, .said switch member lhaving ya portion -of.predetermined resistance and a portion of -dif- .ferent resietancesaidlatter portion being in cir- -cuit between said movable contact andsaidractuating imeans, kand said zrst mentioned portion being in circuitbetween said movable contact and said control fdevice for-predeterm-ining the grela tive control-current flow through saidcontrol device between said terminal and said stationary contact whenthe breaker is closed, whereby to predetermine the current rating of thebreaker.

9. In a circuit breaker having a stationary contact and a companionmovable contact for engagement and disengagement therewith, a movableswitch member for said movable contact, actuating means provided on saidswitch member, a current-responsive control device provided on saidswitch member, said control-device releasably latching said actuatingmeans tc said switch member 4and operable upon overload to release saidactuating means for opening the circuit, and a terminal element incircuit with said control device, said switch member having a portion ofpredetermined resistance and a portion of different resistance, saidlatter portion being in circuit between said movable contact and saidactuating means, and said first mentioned portion being in circuitbetween said movable contact and said control device for predeterminingthe relative control-current flow through said control device betweensaid terminal and said stationary contact when the breaker is closed,whereby to predetermine the current rating of the breaker, said firstmentioned portion having a resistance lower than that of said latterportion.

10. In a circuit breaker having a stationary contact and a companionmovable contact for engagement and disengagement therewith, a movableswitch member for said movable contact, actuating means provided on saidswitch member, a current-responsive control device provided on saidswitch member, said control device releasably latching said actuatingmeans to said switch member and operable upon overload to release saidactuating means for opening the circuit, and a terminal element incircuit with said control device, said switch member having a portion ofpredetermined resistance and a portion of different resistance, saidlatter portion being in circuit between said movable contact and saidactuating means, and said first mentioned portion being in circuitbetween said movable contact and said control device for predeterminingthe relative control-current flow through said control device betweensaid terminal and said stationary contact when the breaker is closed,whereby to predetermine the current rating of the breaker, said rstmentioned portion having a resistance lower than that of said latterportion, said portions being joined in edge-to-edge relation in saidswitch member.

1l. In a circuit breaker having a stationary contact and a companionmovable contact for engagement and disengagement therewith, a movableswitch member for said movable contact, actuating means provided on saidswitch member, a current-responsive control device provided on saidswitch member, said control-device releasably latching said actuatingmeans to said switch member and operable upon overload to release saidactuating means for opening the circuit, and a terminal element incircuit with said control device, said switch member having a portion ofpredetermined resistance and a portion of different resistance, saidlatter portion being in circuit between said movable contact and saidactuating means, and said first mentioned portion being in circuitbetween said movable contact and said control device for predeterminingthe relative control-current flow through said control device betweensaid terminal and said stationary contact when the breaker is closed,

whereby to predetermine the current rating of the breaker, said latterportion being of such a resistance value as to substantially prevent thepassage of current between said movable contact and said actuatingmeans, whereby to obvlate the need for insulation between said switchmember and said actuating means.

12. In a circuit breaker having a stationary contact and a companionmovable contact for engagement and disengagement therewith, a movableswitch member for said movable contact, actuating means, acurrent-responsive control device for releasably latching said actuatingmeans to said switch member and operable upon overload to release saidactuating means for opening the circuit, and a terminal element incircuit with said switch member and said control device to form shuntcurrent paths through said switch member and said control device,respectively, between said movable contact and said terminal element,said switch member having a plurality of serially related portions ofdiierent resistances, respectively, one of said portions'being in serieswith said control device, and the resistances of said portions beingrelated to provide a predetermined overall current-conductivecharacteristic for said switch member, whereby to predetermine thecurrent-rating of said circuit breaker.

13. In a circuit breaker having a stationary contact and a companionmovable contact for engagement and disengagement therewith, a movableswitch member for said movable contact, actuating means, acurrent-responsive con-v trol device for releasably latching saidactuating means to said switch member and operable upon overload torelease said actuating means for opening the circuit, and a terminalelement in circuit with said switch member and said control device toform shunt current paths through said switch member and said controldevice, respectively, between said movable contact and said terminalelement, said switch member having a plurality of serially relatedportions of different resistances, respectively, one of said portionsbeing in series with said control device, and the resistances of saidportions being related to provide a predetermined overallcurrent-conductive characteristic for said switch member, whereby topredetermine the current-rating of said circuit breaker, said oneportion being of low resistance value and another portion having a highresistance value.

14. In a circuit breaker having a stationary contact and a companionmovable contact for engagement and disengagement therewith, a movableswitch member for said movable contact, actuating means provided on saidswitch member, a current-responsive control device provided on saidswitch member, said control-device releasably latching said actuatingmeans to said switch member and operable upon overload to release saidactuating means for opening the circuit, and a terminal element incircuit with said control device, said switch member having a portion ofpredetermined resistance and a portion of different resistance, saidlatter portion being in circuit between said movable contact and saidactuating means, and said rst mentioned portion being in circuit betweensaid movable contact and said control device for predetermining therelative control-current flow through said control device between saidterminal and said stationary contact when the breaker is closed, wherebyto predetermine the 9 current rating of the breaker, and an electricalconnector of predetermined resistance between said terminal element andsaid switch member, whereby said current-rating is a function of thecurrent-conductive characteristic of said connector.

15. In a circuit breaker having a stationary contact and a companionmovable contact for engagement and disengagement therewith, a movableswitch member for said movable contact, actuating means provided on saidswitch member, a current-responsive control device provided on saidswitch member, said control-device releasably latching said actuatingmeans to said switch member and operable upon overload to release saidactuating means for opening the circuit, and a terminal element incircuit with said control device, said switch vmember having a portionof predetermined resistance and a portion of different resistance, saidlatter portion being in circuit between said movable contact and saidactuating means, and said first mentioned portion being in circuitbetween said movable contact and said control device for predeterminingthe relative control-current flow through said control device betweensaid terminal and said stationaryr contact when the breaker is closed,whereby to predetermine the current rating of the breaker, and anelectrical connector of predetermined resistance between said terminalelement and said switch member, whereby said current-rating is afunction of the current conductive characteristic of said connector,said rst mentioned portion having a resistance lower than that of saidlatter portion.

16. A system for Calibrating circuit breakers of the type having aninput terminal and an output terminal and means for providing parallelcurrent paths through the breaker between said terminals in the closedcondition of the breaker, a pair of engageable and disengageablecontacts common to said paths, one of said paths including a movablecurrent conductive switch member operable upon overload to disengagesaid contacts for interrupting said parallel paths to break the circuitthrough the breaker and the other path including a current-conductivecontrol element operable in resp-onse to predetermined current flowtherethrough to effect said operation of said switch member; said systemcomprising the establishment of a basic current-rating for each circuitbreaker as a function of the current-conductive characteristic of theswitch member thereof for predetermining therelative division of thecurrent flow through said parallel paths.

17. A system for calibrating circuit breakers of the type having aninput terminal and an output terminal and means for providing parallelcurrent paths through the breaker between said terminals in the closedcondition of the breaker, a pair of engageable and disengageablecontacts common to said paths, one of said paths including a movablecurrent conductive switch member operable upon overload to disengagesaid contacts for interrupting said parallel paths to break the circuitthrough the breaker and the other path including a current-conductivecontrol element operable in response to predetermined current flowtherethrough to effect said operation of said switch member; said systemcomprising the establishment of a basic current-rating for each circuitbreaker as a function of the current-conductive characteristic of theswitch member thereof for predetermining the relative division of thecurrent ow through said parallel paths, and then varying said basiccurrent rating by including in the current path which includes saidmovable switch member an electrical connector of predeterminedresistance value between said switch member and one of said terminals.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,071,848 Lindstrom Feb. 23, 1937 2,126,412 Rowe Aug. 9, 19382,132,627 Jackson Oct. 11, 1938 2,370,206 Taylor Feb. 27, 1945 2,443,230De C'oursey June 15, 1948 2,478,541 McCracken Aug. 9, 1949 2,636,958Dorfman et al Apr. 28, 1953

